...we spent several nights in our more usual spot behind Paris Las Vegas
and it's sister properties on either side, Bally's and Planet Hollywood. That's our favorite spot in LV because it is a short walk to the strip and several very nice properties; more details and a photo can be found in parts of these two posts:
http://ourodyssey.blogspot.com/2012/02/vegas-wedding.html
http://ourodyssey.blogspot.com/2012/02/au-revoir-paris.html

Thanks to Sean, http://ourodyssey.blogspot.com, for his report on the Casino Camper Yahoo! Group http://autos.groups.yahoo.com/group/casinocamper/ reprinted above.

There has been no problem parking behind Bally's near the fenced off employee parking area. We will be here a total of 3 nights and have not been approached by security at all. There are other rigs here who were here when we arrived as well as semis that arrive nightly. The best entrance is heading west on Flamingo past the employment building on the south side of the street. The entrance is directly across from the Westin. It is not the cleanest and is a little loud when the windows are down but it is the best and closest boondocking site near the strip that we have found.